Manifest Management

Kubernetes speaks YAML. But managing raw YAML for 50 services across 3 environments (Dev, Staging, Prod) is a nightmare.

Templating Engines

Helm (The Package Manager)

Helm uses Go templates ({{ .Values.image }}).

• Pros: Standard, huge ecosystem of pre-made charts (Redis, Prometheus).
• Cons: Template logic gets messy. Debugging whitespace in YAML templates is painful.

Kustomize (The Overlayer)

Kustomize uses a "Base" and "Overlay" approach.

• Base: deployment.yaml (Generic).
• Prod Overlay: Patch the base to set replicas: 5.
• Pros: No templating language. Pure YAML. Built into kubectl.

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GitOps (ArgoCD / Flux)

Stop running kubectl apply from your laptop.

GitOps uses a Git repository as the "Source of Truth".

1. Repo: Contains your Helm/Kustomize files.
2. Controller (ArgoCD): Runs inside the cluster. It watches the Git repo.
3. Sync: If the Repo differs from the Cluster state, ArgoCD forces the cluster to match the repo.

• Drift Detection: If someone manually changes a setting in the cluster, ArgoCD alerts that the cluster is "Out of Sync" with Git.